Copolycarbonate diol and thermoplastic polyurethane obtained therefrom

ABSTRACT

A copolycarbonate diol comprising:  
     (a) recurring units each represented by the following formula (1):  
                 
 
     (b) recurring units each independently represented by the following formula (2):  
                 
 
     wherein n is 4, 5 or 6; and  
     (c) terminal hydroxyl groups, wherein the copolycarbonate diol has a number average molecular weight of from 300 to 20,000, and wherein the amount of the recurring units (a) is from 10 to 90% by mole, based on the total molar amount of the recurring units (a) and (b). A thermoplastic polyurethane obtained by copolymerizing the above-mentioned copolycarbonate diol with a polyisocyanate.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a copolycarbonate diol. Moreparticularly, the present invention is concerned with a copolycarbonatediol comprising:

[0003] (a) recurring units each represented by the following formula(1):

[0004] (b) recurring units each independently represented by thefollowing formula (2):

[0005] wherein n is 4, 5 or 6; and

[0006] (c) terminal hydroxyl groups,

[0007] wherein the copolycarbonate diol has a number average molecularweight of from 300 to 20,000, and wherein the amount of the recurringunits (a) is from 10 to 90% by mole, based on the total molar amount ofthe recurring units (a) and (b).

[0008] The copolycarbonate diol of the present invention is a liquidhaving low viscosity. Therefore, the copolycarbonate diol of the presentinvention is easy to handle, as compared to the conventionalpolycarbonate diols which are solids or highly viscous liquids. Hence,the copolycarbonate diol of the present invention is advantageous forvarious uses, such as a raw material for producing a thermoplasticelastomer (such as a thermoplastic polyurethane) used for producingvarious shaped articles (for example, a spandex, which is a polyurethaneelastomeric fiber); a component for a coating material or an adhesive;and a polymeric plasticizer.

[0009] The present invention is also concerned with a thermoplasticpolyurethane obtained from the above-mentioned copolycarbonate diol anda polyisocyanate. The thermoplastic polyurethane of the presentinvention exhibits excellent properties with respect to flexibility,heat resistance, low temperature properties, weathering resistance,strength, and molding processability. Therefore, the thermoplasticpolyurethane of the present invention is extremely useful as a materialfor producing various shaped articles, such as automobile parts, partsfor household electric appliances, toys and sundry goods. Especially,the thermoplastic polyurethane of the present invention is useful forproducing shaped articles which are required to have high strength, suchas hoses, sheets and industrial belts; and shaped articles which arerequired to have high flexibility, such as interior and exterior partsfor automobiles (for example, window moles, bumpers, skin parts for aninstrument panel, and grips), spandexes, bands for wristwatches, andshoe soles.

[0010] 2. Prior Art

[0011] A polyurethane and a urethane-, ester- or amide-basedthermoplastic elastomer are used in the art. The soft segments of thepolyurethane and thermoplastic elastomer are composed of structuralunits formed from a polyester polyol and/or a polyether polyol, each ofwhich has a hydroxyl group at each of the molecular terminals thereof(see, for example, U.S. Pat. Nos. 4,362,825 and 4,129,715). A polyesterpolyol, such as a polyadipate polyol, has poor hydrolysis resistance.Due to the poor hydrolysis resistance, for example, a polyurethanecontaining, as soft segments, structural units formed from a polyesterpolyol has a disadvantage in that tackiness and cracks are likely tooccur on the surfaces of shaped articles of the polyurethane within arelatively short period of time. Therefore, the use of such apolyurethane is considerably limited. On the other hand, a polyurethanecontaining, as soft segments, structural units formed from a polyetherpolyol has good hydrolysis resistance and excellent flexibility.However, the polyurethane has a disadvantage in that it has poorresistance to light and oxidative degradation. The disadvantages ofthese polyurethanes are, respectively, attributed to the presence ofester groups in the polymer chain and the presence of ether groups inthe polymer chain.

[0012] With respect to the polyester- or polyamide-based thermoplasticelastomer containing, as soft segments, structural units formed from apolyester polyol or a polyether polyol, there has recently been a demandfor improvement in resistance to heat, light, hydrolysis and oil. Inaccordance with the increased demand for such improvement, the samedisadvantages as accompanying the above-mentioned polyurethanes havebeen pointed out with respect also to the thermoplastic elastomer.

[0013] A polycarbonate polyol prepared from 1,6-hexanediol is used as apolyol usable for forming soft segments which have excellent resistanceto hydrolysis, light, oxidative degradation, heat and the like. Theseresistances are due to the fact that carbonate linkages in the polymerchain exhibit extremely high chemical stability.

[0014] However, the polycarbonate polyol prepared from 1,6-hexanediol iscrystalline and hence is a solid at room temperature. Therefore, forproducing a polyurethane from the polycarbonate polyol and apolyisocyanate, it is necessary that the polycarbonate polyol be heatedand melted before effecting a reaction with the polyisocyanate, so thata long period of time is required for producing a polyurethane. In thisrespect, the polycarbonate polyol poses a problem in handling.

[0015] As mentioned above, when this polycarbonate polyol is used forforming soft segments of a polyurethane, the polyurethane has improvedresistance to hydrolysis, light, oxidative degradation and heat.However, the polyurethane has defects in flexibility and low temperatureproperties. Especially, the polyurethane is defective in that itexhibits markedly poor elastic recovery at low temperatures. Due to suchdefects, the polyurethane poses a problem in that it exhibits poorstringiness and hence has poor spinnability. The reason for the poorstringiness is that crystallization is likely to occur in the softsegments of the polyurethane, thus leading to a lowering of theelasticity of the polyurethane. Such easy occurrence of crystallizationin the soft segments results from the high crystallinity of thepolycarbonate polyol prepared from 1,6-hexanediol.

[0016] In order to solve these problems, it has been proposed tocopolymerize 1,6-hexanediol with a polyhydric alcohol having a sidechain so as to produce a copolycarbonate polyol.

[0017] For example, in Unexamined Japanese Patent Application Laid-OpenSpecification No. Hei 10-292037, a polycarbonate containing recurringunits derived from 1,6-hexanediol and neopentyl glycol, is disclosed.This polycarbonate is used as a material for a polyurethane, a polyamideelastomer and a polyester elastomer, and as a component for a coatingmaterial and an adhesive.

[0018] In Japanese Patent No. 2781104 (corresponding to EP 562 577), apolycarbonate polyol containing recurring units derived from a diolhaving a branched structure and a polyhydric alcohol comprising atetrahydric to hexahydric alcohol, is disclosed. This polycarbonatepolyol is used as a binder for a coating material.

[0019] In Unexamined Japanese Patent Application Laid-Open SpecificationNo. Hei 2-49025 (corresponding to EP 343 572), a polycarbonate diolcontaining recurring units derived from a C₃-C₂₀ polyhydric alcoholhaving a side chain and 1,6-hexanediol, is disclosed. This polycarbonatediol is used as a material for producing a polyurethane.

[0020] In Japanese Patent No. 2506713, a polycarbonate diol containingrecurring units derived from 2-methyl-1,8-octanediol or recurring unitsderived from a diol comprised mainly of 2-methyl-1,8-octanediol and1,9-nonanediol, is disclosed. This polycarbonate diol is used as amaterial for producing a polyurethane, a polyamide elastomer and apolyester elastomer, and is used in the fields of a coating material andan adhesive.

[0021] WO 98/27133 discloses a polycarbonate polyol containing recurringunits derived from a diol having a side chain which contains two loweralkyl groups, and a polyurethane produced using, as a soft segment, thispolycarbonate polyol.

[0022] These polycarbonate polyols have a side chain, and, therefore,the elastomers (such as polyurethanes) produced using, as a softsegment, these polycarbonate polyols, have a side chain, i.e., they havea branched structure. Due to such branched structure, the polycarbonatepolyols have a problem in that the elastomers produced using thesepolycarbonate polyols exhibit poor mechanical properties, as compared tothose of elastomers which have no side chains.

[0023] When a thermoplastic elastomer is produced using, as a softsegment, a polycarbonate polyol prepared from a bulky polyhydric alcohol(e.g., neopentyl glycol) which contains a quaternary carbon atom havingtwo side chains bonded thereto, the strength of the thermoplasticelastomer is lowered depending on the content of the recurring unitsderived from the above-mentioned bulky polyhydric alcohol.

[0024] When a thermoplastic elastomer is produced using, as a softsegment, a polycarbonate polyol prepared from a polyhydric alcohol whichcontains a tertiary carbon atom having one side chain bonded thereto,there is a problem in that the heat aging resistance of thethermoplastic elastomer is lowered. The reason for occurrence of such alow heat aging resistance of the thermoplastic elastomer is that thehydrogen atom which is bonded to the tertiary carbon atom having oneside chain is likely to become a radical so as to be easily eliminatedfrom the tertiary carbon atom, as compared to a hydrogen atom which isbonded to a secondary carbon atom having no side chains.

[0025] As another measure for lowering the crystallinity of apolycarbonate polyol prepared from 1,6-hexanediol, it has been proposedthat 1,6-hexanediol is copolymerized with a diol having no side chainsso as to produce a copolycarbonate diol.

[0026] For example, Examined Japanese Patent Application Publication No.Hei 5-29648 (corresponding to EP 302 712 and U.S. Pat. Nos. 4,855,377and 5,070,173) discloses an aliphatic copolycarbonate diol producedusing 1,5-pentanediol and 1,6-hexanediol.

[0027] Generally, even when a homopolymer which is obtained byhomopolymerizing a monomer is crystalline, a copolymer which is obtainedby copolymerizing the monomer with an appropriate comonomer has lowcrystallinity, as compared with the homopolymer; the reason for this isthat the structural regularity of the copolymer is disordered by thecomonomer units. In the case of a copolycarbonate polyol containing1,6-hexanediol units, when the comonomer diol units are, for example,those derived from a diol which contains an odd number of methylenegroups, such as 1,5-pentanediol, the structural regularity of thecopolycarbonate polyol is likely to be greatly disordered, as comparedto the case where the comonomer diol units are those derived from a diolwhich contains an even number of methylene groups.

[0028] However, this copolycarbonate diol is a solid or a viscousliquid, so that the handling properties of the copolycarbonate diol areunsatisfactory, depending on the use thereof.

[0029] In recent years, a thermoplastic polyurethane which is producedusing, as a soft segment, a copolycarbonate diol prepared from a mixtureof 1,6-hexanediol and 1,4-butanediol or 1,5-pentanediol is attractingattention because of its great advantages. (The above-mentionedcopolycarbonate diol is disclosed in Examined Japanese PatentApplication Publication No. Hei 5-029648 (which is mentioned above) andJapanese Patent No. 3128275; and the above-mentioned thermoplasticpolyurethane is disclosed in Unexamined Japanese Patent ApplicationLaid-Open Specification No. Hei 5-51428 and Japanese Patent No. 1985394(corresponding to EP 302 712 and U.S. Pat. Nos. 4,855,377 and5,070,173).) Specifically, such thermoplastic polyurethane hasadvantages in that it has remarkably excellent properties with respectto flexibility and low temperature properties, as well as the sameexcellent properties as mentioned above and as achieved by using, as asoft segment, a polycarbonate diol prepared from 1,6-hexanediol, i.e.,excellent resistance to hydrolysis, light, oxidative degradation andheat.

[0030] However, in the course of the studies of the present inventors,it was found that the thermoplastic polyurethane produced using, as asoft segment, the above-mentioned copolycarbonate diol has a problem inthat the flexibility is still unsatisfactory and hence the use of thethermoplastic polyurethane is limited.

[0031] With respect to polycarbonate diols other than those mentionedabove, there are documents which refer to the use of a polycarbonatediol prepared from 1,3-propanediol.

[0032] For example, in WO 01/72867, there is disclosed a thermoplasticpolyurethane produced using, as a soft segment, a polycarbonate diol inwhich the diol units are composed only of 1,3-propanediol units.However, this thermoplastic polyurethane is hard and exhibits highmodulus (that is, the elongation of the thermoplastic polyurethane isunsatisfactory), rendering it difficult to use the thermoplasticpolyurethane in the same application fields as those of the ordinaryelastomers. The reason for this has not yet been completely elucidated;however, the reason is presumed to be as follows.

[0033] In the above-mentioned polycarbonate diol, each recurring unithas only three methylene groups (derived from 1,3-propanediol), so thatthe ratio of the carbonate linkages in the polycarbonate diol moleculeis high. The flexibility of such polycarbonate diol molecule is lowered,and hence, the thermoplastic polyurethane produced using suchpolycarbonate diol exhibits low elasticity.

[0034] Examined Japanese Patent Application Publication No. Hei 8-32777discloses a process for rapidly producing a polycarbonate diol,comprising subjecting a mixture of a dialkyl carbonate and a hydroxycompound or a mixture of a diaryl carbonate and a hydroxy compound to atransesterification reaction in the presence of a titanium compound or atin compound. This process is intended to rapidly produce a high qualitypolycarbonate diol which is less likely to suffer discoloration.

[0035] In this prior art document, as examples of hydroxy compounds,1,3-propanediol, 1,4-butanediol, 1,5-pentanediol and 1,6-hexanediol aredescribed. However, in this prior art document, no polycarbonate diol isactually produced using 1,3-propanediol. Further, no polyurethane isproduced using a polycarbonate diol, and no evaluation is made withrespect to the properties of a polyurethane.

[0036] Unexamined Japanese Patent Application Laid-Open SpecificationNo. Hei 4-239024 discloses the following process. First, a reactionmixture which contains a low molecular weight polycarbonate diol isproduced. A diaryl carbonate is added to the reaction mixture produced,and a reaction is performed while removing a by-produced alcohol,thereby producing a high molecular weight polycarbonate diol. Thisprocess is intended to produce a polycarbonate diol using a monomer in asmall amount.

[0037] In this prior art document, as examples of diols which are usableas a material for producing the polycarbonate diol, 1,3-propanediol,1,4-butanediol, 1,5-pentanediol and 1,6-hexanediol are described.However, in this prior art document, no polycarbonate diol is producedusing 1,3-propanediol. Further, no polyurethane is produced using apolycarbonate diol, and naturally, any evaluation is not made withrespect to the properties of a polyurethane.

[0038] As apparent from the foregoing, conventionally, there has not yetbeen obtained a polycarbonate diol which is suitable as a material forproducing a thermoplastic polyurethane which is advantageous not only inthat it exhibits excellent resistance to hydrolysis, light, oxidativedegradation and heat, but also in that it exhibits excellent propertieswith respect to flexibility and low temperature properties.

SUMMARY OF THE INVENTION

[0039] In this situation, the present inventors have made extensive andintensive studies with a view toward developing a thermoplasticpolyurethane which is advantageous not only in that it exhibitsexcellent resistance to hydrolysis, light, oxidative degradation andheat, but also in that it exhibits excellent flexibility comparable tothat of a polyether-based thermoplastic polyurethane, and exhibitsexcellent low temperature properties, especially excellent elasticrecovery at low temperatures, and with a view toward developing apolycarbonate diol which is suitable as a material for producing thethermoplastic polyurethane and which is easy to handle. As a result ofthese studies, it has unexpectedly been found that a copolycarbonatediol which is obtained by copolymerizing at least one diol selected fromthe group consisting of 1,4-butanediol, 1,5-pentanediol and1,6-hexanediol with 1,3-propanediol, is advantageous not only in that itexhibits excellent handling properties, but also in that a thermoplasticpolyurethane which is obtained by copolymerizing this copolycarbonatediol with a polyisocyanate exhibits excellent properties with respect toflexibility and low temperature properties, as well as excellentresistance to hydrolysis, light, oxidative degradation and heat.

[0040] The above-mentioned copolycarbonate diol comprises

[0041] (a) recurring units each represented by the following formula(1):

[0042] (b) recurring units each independently represented by thefollowing formula (2):

[0043] wherein n is 4, 5 or 6; and

[0044] (c) terminal hydroxyl groups.

[0045] The present invention has been completed on the basis of thesenovel findings.

[0046] Accordingly, it is an object of the present invention to providea copolycarbonate diol which exhibits excellent handling properties andis suitable as a material for producing a thermoplastic polyurethanewhich exhibits excellent properties with respect to flexibility and lowtemperature properties, as well as excellent resistance to hydrolysis,light, oxidative degradation and heat.

[0047] It is another object of the present invention to provide athermoplastic polyurethane exhibiting excellent properties, which isobtained by copolymerizing the above-mentioned copolycarbonate diol witha polyisocyanate.

[0048] The foregoing and other objects, features and advantages of thepresent invention will be apparent to those skilled in the art from thefollowing detailed description and appended claims.

DETAILED DESCRIPTION OF THE INVENTION

[0049] According to the present invention, there is provided acopolycarbonate diol comprising:

[0050] (a) recurring units each represented by the following formula(1):

[0051] (b) recurring units each independently represented by thefollowing formula (2):

[0052] wherein n is 4, 5 or 6; and

[0053] (c) terminal hydroxyl groups,

[0054] wherein the copolycarbonate diol has a number average molecularweight of from 300 to 20,000, and wherein the amount of the recurringunits (a) is from 10 to 90% by mole, based on the total molar amount ofthe recurring units (a) and (b).

[0055] For easy understanding of the present invention, the essentialfeatures and various preferred embodiments of the present invention areenumerated below.

[0056] 1. A copolycarbonate diol comprising:

[0057] (a) recurring units each represented by the following formula(1):

[0058] (b) recurring units each independently represented by thefollowing formula (2):

[0059] wherein n is 4, 5 or 6; and

[0060] (c) terminal hydroxyl groups,

[0061] wherein the copolycarbonate diol has a number average molecularweight of from 300 to 20,000, and wherein the amount of the recurringunits (a) is from 10 to 90% by mole, based on the total molar amount ofthe recurring units (a) and (b).

[0062] 2. The copolycarbonate diol according to item 1 above, which hasa number average molecular weight of from 500 to 10,000.

[0063] 3. The copolycarbonate diol according to item 1 or 2 above,wherein the amount of the recurring units (a) is from 20 to 80% by mole,based on the total molar amount of the recurring units (a) and (b).

[0064] 4. A thermoplastic polyurethane obtained by copolymerizing thecopolycarbonate diol of any one of items 1 to 3 above with apolyisocyanate.

[0065] Hereinbelow, the present invention will be described in detail.

[0066] The copolycarbonate diol of the present invention comprises:

[0067] (a) recurring units each represented by the following formula(1):

[0068] (b) recurring units each independently represented by thefollowing formula (2):

[0069] wherein n is 4, 5 or 6; and

[0070] (c) terminal hydroxyl groups.

[0071] Due to such structure, the structural regularity of thecopolycarbonate diol of the present invention is low, as compared tothat of a polycarbonate diol which is a homopolymer.

[0072] The recurring unit (a) contains only three methylene groups,i.e., a small odd number of methylene groups. A recurring unitcontaining a small odd number of methylene groups tends to be moreeffective for disordering the structural regularity of a copolycarbonatediol than other recurring units. Therefore, by virtue of the use of therecurring unit (a), the crystallinity of the copolycarbonate diol islowered, so that the copolycarbonate diol is an amorphous polymer suchthat a crystallization temperature and a melting temperature are notobserved in analyses by differential scanning calorimetry (DSC). As aresult, the viscosity of the copolycarbonate diol is lowered and thecopolycarbonate diol is easy to handle. In addition, a thermoplasticpolyurethane obtained using the copolycarbonate diol exhibits improvedflexibility. Further, a thermoplastic elastomer (especially athermoplastic polyurethane) produced using the amorphous copolycarbonatediol exhibits excellent stringiness.

[0073] In the copolycarbonate diol of the present invention, the amountof the recurring units (a) is from 10 to 90% by mole, preferably from 20to 80% by mole, more preferably from 30 to 70% by mole, based on thetotal molar amount of the recurring units (a) and (b).

[0074] Such copolycarbonate diol is generally a viscous liquid at roomtemperature, but the viscosity of the copolycarbonate diol is lower thanthose of the conventional polycarbonate diols. Therefore, when thecopolycarbonate diol of the present invention is used as a material forproducing a thermoplastic elastomer (such as a thermoplasticpolyurethane) or as a component for a coating material or an adhesive,the copolycarbonate diol is easy to handle.

[0075] It is especially preferred that a thermoplastic polyurethane isproduced using a copolycarbonate diol of the present invention whereinthe amount of the recurring units (a) is from 30 to 70% by mole, basedon the total molar amount of the recurring units (a) and (b). Athermoplastic polyurethane produced using such copolycarbonate diolexhibits excellent properties with respect not only to flexibility andmodulus (that is, the modulus is low), but also to elongation and impactresilience. That is, such thermoplastic polyurethane exhibits extremelyadvantageous properties which are similar to those of a vulcanizedrubber.

[0076] The number average molecular weight of the copolycarbonate diolof the present invention is from 300 to 20,000, preferably from 500 to10,000, more preferably from 800 to 3,000.

[0077] When the number average molecular weight of the copolycarbonatediol is less than 300, the flexibility and low temperature properties ofthe thermoplastic polyurethane produced using the copolycarbonate dioltends to be unsatisfactory. On the other hand, when the number averagemolecular weight of the copolycarbonate diol is more than 20,000, themolding processability of the thermoplastic polyurethane produced usingthe copolycarbonate diol is lowered.

[0078] In the present invention, the number average molecular weight ofthe copolycarbonate diol is determined from the hydroxyl value of thecopolycarbonate diol, by the following method. More specifically stated,first, the hydroxyl (OH) value of the copolycarbonate diol is determinedby the neutralization titration method (JIS K 0070-1992), which usesacetic anhydrate, pyridine and an ethanol solution of potassiumhydroxide. The number average molecular weight (Mn) is calculated fromthe OH value in accordance with the following formula:

Mn=56.1×2×1,000÷OH value.

[0079] It is preferred that substantially all terminal groups of thecopolycarbonate diol of the present invention are hydroxyl groups. Theterminal groups of the copolycarbonate diol can be determined bymeasuring the acid value of the copolycarbonate diol or analyzing thecopolycarbonate diol by ¹³C-NMR (¹³C-nuclear magnetic resonance)spectroscopy. The acid value of a substance is the amount (mg) ofpotassium hydroxide (KOH) required for neutralizing the acidic groups in1 g of the substance. When the acid value of the copolycarbonate diol is0.01 or less, the copolycarbonate diol contains substantially no acidgroups and, therefore, it is confirmed that substantially all terminalgroups of the copolycarbonate diol are hydroxyl groups.

[0080] Hereinbelow, an explanation is made with respect to the processfor producing the copolycarbonate diol of the present invention.

[0081] The copolycarbonate diol of the present invention can be obtainedby subjecting to a polymerization reaction the following components:

[0082] (I) 1,3-propanediol;

[0083] (II) at least one diol selected from the group consisting of1,4-butanediol, 1,5-pentanediol and 1,6-hexanediol; and

[0084] (III) a carbonate compound.

[0085] The amount of 1,3-propanediol (hereinafter, frequently referredto as the “diol (I)”) is from 10 to 90% by mole, preferably from 20 to80% by mole, more preferably from 30 to 70% by mole, based on the totalmolar amount of the diols (I) and (II).

[0086] Examples of carbonate compounds (III) above include dialkylcarbonates, such as dimethyl carbonate, diethyl carbonate and dibutylcarbonate; alkylene carbonates, such as ethylene carbonate,1,2-propylene carbonate and trimethylene carbonate; and diarylcarbonates, such as diphenyl carbonate. Among these, alkylene carbonatesare preferred, since when alkylene carbonates are used for producing thecopolycarbonate diol of the present invention, a copolycarbonate diol inwhich substantially all terminal groups are hydroxyl groups can beeasily obtained. Such copolycarbonate diol is especially advantageous asa material for producing a thermoplastic polyurethane.

[0087] Among alkylene carbonates, ethylene carbonate is preferred, sincethe use of ethylene carbonate provides the following advantage.

[0088] In the above-mentioned polymerization reaction, there isby-produced a compound containing a hydroxyl group, which is derivedfrom the carbonate compound (III) (hereinafter, this by-product isreferred to as a “hydroxyl group-containing by-product”). Whenethylene-carbonate is used as the carbonate compound (III), the hydroxylgroup-containing by-product is ethylene glycol. Ethylene glycol has arelatively low boiling point and hence can be easily removed from thereaction system.

[0089] With respect to the amount of the carbonate compound (III), thereis no particular limitation. However, in general, the molar ratio of thecarbonate compound (III) to the total molar amount of the diols (I) and(II) is from 20:1 to 1:20.

[0090] It is preferred that the copolycarbonate diol of the presentinvention is produced using only the above-mentioned components (I) to(III). The reason for this preference is that there can be obtainedadvantages in that the polymerization reaction is almost not limited bythe melting points and boiling points of the diols (I) and (II), andthat a thermoplastic polyurethane produced using the obtainedcopolycarbonate diol exhibits especially improved flexibility. However,if desired, a polyhydric alcohol other than the diols (I) and (II) canbe used in combination with the diols (I) and (II) as long as theeffects of the present invention are not adversely affected.

[0091] Examples of polyhydric alcohols include linear diols, such as1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol,1,11-undecanediol and 1,12-dodecanediol; branched diols, such asneopentyl glycol, 3-methylpentane-1,5-diol, 2-ethyl-1,6-hexanediol,2-methyl-1,3-propanediol and 2-methyl-1,8-octanediol; cyclic diols, suchas 1,3-cyclohexanediol, 1,4-cyclohexanediol,2,2′-bis(4-hydroxycyclohexyl)propane and 1,4-cyclohexanedimethanol; andalcohols containing three or more hydroxyl groups, such as trimethylolethane, trimethylol propane, hexanetriol and pentaerythritol.

[0092] The suitable amount of the polyhydric alcohol varies depending onthe type of the polyhydric alcohol.

[0093] When a linear diol is used as the polyhydric alcohol, the amountof the linear diol is generally 20% by mole or less, preferably 10% bymole or less, based on the total molar amount of the diols (I) and (II).

[0094] When a branched diol and/or a cyclic diol is used as thepolyhydric alcohol, it is preferred that the amount of the polyhydricalcohol is less than in the case where a linear diol is used as thepolyhydric alcohol. Specifically, the amount of a branched diol and/or acyclic diol is generally 15% by mole or less, preferably 5% by mole orless, based on the total molar amount of the diols (I) and (II).

[0095] The reason why, when a branched diol and/or a cyclic diol is usedas the polyhydric alcohol, it is preferred that the amount of thepolyhydric alcohol is less than in the case where a linear diol is usedas the polyhydric alcohol, is as follows. When a branched diol and/or acyclic diol is used for producing a copolycarbonate diol, the strengthand heat aging resistance of a thermoplastic polyurethane produced usingthe copolycarbonate diol tend to be lower than those of a thermoplasticpolyurethane produced using a copolycarbonate diol produced by a processusing a linear diol as the polyhydric alcohol.

[0096] When an alcohol containing three or more hydroxyl groups is usedas the polyhydric alcohol, a reaction product obtained by thepolymerization reaction performed for producing the copolycarbonate diolof the present invention, is a copolycarbonate polyol containing threeor more hydroxyl groups. In the present invention, such copolycarbonatepolyol is also regarded as the copolycarbonate diol of the presentinvention.

[0097] In the case where an alcohol containing three or more hydroxylgroups is used as the polyhydric alcohol, the amount of the polyhydricalcohol is generally 10% by mole or less, preferably 5% by mole or less,based on the total molar amount of the diols (I) and (II). When theamount of the polyhydric alcohol is too large, too large an amount ofcrosslinkages are introduced into a polyurethane produced using thecopolycarbonate diol, thus leading to a lowering of the thermoplasticityof the polyurethane.

[0098] With respect to the method for performing the polymerizationreaction, there is no particular limitation, and the polymerizationreaction can be performed by using conventional methods, such as thevarious methods described in “Polymer Reviews”, Vol. 9, pp. 9-20,written by H. Schnell (published by Interscience Publishers, U.S.A.,1964), and the method described in the above-mentioned Examined JapanesePatent Application Publication No. Hei 5-29648.

[0099] Hereinbelow, an explanation is made of an example of a method forproducing the copolycarbonate diol of the present invention, whichcomprises the following two steps:

[0100] (1) performing a polymerization reaction of the above-mentionedraw materials (I) to (III) and optionally the polyhydric alcohol, whileremoving the hydroxyl group-containing by-product from the reactionsystem, to thereby obtain a copolycarbonate prepolymer; and

[0101] (2) performing a self-condensation of the above-obtainedcopolycarbonate prepolymer,

[0102] to thereby obtain the copolycarbonate diol of the presentinvention.

[0103] First, an explanation is made of the step (1).

[0104] In the step (1), the diol (I) (1,3-propanediol), the diol (II)(at least one diol selected from the group consisting of 1,4-butanediol,1,5-pentanediol and 1,6-hexanediol), the carbonate compound (III) andoptionally the polyhydric alcohol are mixed together, and the resultantmixture is subjected to a polymerization reaction, to thereby obtain acopolycarbonate prepolymer.

[0105] Hereinbelow, an explanation is made taking as an example the casewhere only the diols (I) and (II) and the carbonate compound (III) areused as the raw materials. With respect to the case where the polyhydricalcohol is used as an optional raw material, the polyhydric alcohol isconsidered to show substantially the same behavior as that of the diol(II), in the polymerization reaction.

[0106] The main reactions involved in the polymerization reaction arethe addition reaction, namely, the reaction of addition of the diol (I)or (II) to the carbonate compound (III), and the transesterificationreaction between the reaction product of the addition reaction and thediol (I) or (II). As the transesterification reaction proceeds, thehydroxyl group-containing by-product is eliminated from the carbonatecompound (III). Since the transesterification reaction is an equilibriumreaction, when the hydroxyl group-containing by-product accumulates inthe reaction system, the polymerization does not satisfactorily advance.Therefore, it is preferred that the polymerization reaction is performedwhile removing the hydroxyl group-containing by-product from thereaction system.

[0107] More specifically, it is preferred that the polymerizationreaction of the step (1) is performed in the following manner: a vaporcontaining the hydroxyl group-containing by-product which is producedduring the polymerization reaction, is generated, and the thus generatedvapor is condensed to obtain a condensate, and at least a part of thethus obtained condensate is removed from the reaction system. Forfacilitating the generation of the vapor, it is preferred that thepolymerization reaction is performed under reduced pressure.

[0108] In this instance, for increasing the efficiency of the removal ofthe hydroxyl group-containing by-product, a method may be adopted inwhich an inert gas (such as nitrogen, argon, helium, carbon dioxide anda lower hydrocarbon gas) which does not have an adverse effect on thepolymerization reaction, is introduced into the reaction system so thatthe hydroxyl group-containing by-product is removed in a form entrainedby the inert gas.

[0109] For suppressing the distillation of the diols (I), (II) and thecarbonate compound (III), and for efficiently removing the hydroxylgroup-containing by-product from the reaction system, it is preferredthat the polymerization reaction is performed in a reactor equipped witha fractionating column. When using a fractionating column, theseparating capability thereof is important. Hence, a fractionatingcolumn is used which generally has a number of theoretical plates of 5or more, preferably 7 or more.

[0110] A fractionating column is used generally in such a form asequipped, at its top, with an appropriate reflux condenser. The refluxcondenser is used for condensing the vapor ascending inside of thefractionating column, to form a condensate, and for causing at least apart of the condensate to flow down inside of the fractioning column,back to the reactor. Use of such a fractionating column is advantageousin that the vapor containing the hydroxyl group-containing by-product(which ascends inside of the fractionating column) and the condensate(which flows down inside of the fractionating column) contact each otherin a counter flow, thereby causing the hydroxyl group-containingby-product in the condensate to move into the vapor, and also causingthe diols (I) and (II) and the carbonate compound (III) in the vapor tomove into the condensate, to thereby facilitate the efficient removal ofthe hydroxyl group-containing by-product from the reaction system.

[0111] In the process for producing the copolycarbonate diol of thepresent invention, it is preferred that the polymerization reaction isperformed by using the reactor as mentioned above, while generating avapor containing the hydroxyl group-containing by-product, and thegenerated vapor is condensed into a condensate by means of a refluxcondenser, followed by removal of a part of the obtained condensate as adistillate from the reaction system while causing the remainder of thecondensate to flow down inside of the fractioning column, back to thereactor.

[0112] By setting in an appropriate range the volume ratio of thecondensate returned to the reaction vessel, relative to the condensateremoved as a distillate from the reaction system (i.e., the refluxratio), advantages can be obtained in that the distillation of the diols(I), (II) and the carbonate compound (III) can be suppressed, therebyincreasing the efficiency of the reaction. With respect to theappropriate range of reflux ratio, although it varies depending on theperformance of the fractionating column, the reflux ratio is generallyin the range of from 3 to 10, preferably from 3 to 7.

[0113] In addition, for efficiently performing the polymerizationreaction, it is important to appropriately control the amount of thevapor (containing the hydroxyl group-containing by-product) whichascends inside of the fractionating column per unit time (i.e., it isimportant to appropriately control the so-called “throughput”). When thethroughput is too small, the rate of removal of the hydroxylgroup-containing by-product becomes low and hence the reaction timebecomes long. On the other hand, when the throughput is too large, theefficiency of the reaction is decreased, due to, e.g., the distillationof the diols (I) and (II). Therefore, it is preferred that thethroughput is as great as possible, as long as the efficiency of thereaction is not decreased.

[0114] The control of the reflux ratio and throughput is performed byappropriately controlling the temperature and pressure for the reaction.The appropriate control of the reflux ratio and throughput is extremelyadvantageous in that the polymerization reaction can be completed in arelatively short time, thereby improving not only the productivity ofthe copolycarbonate diol but also the quality thereof.

[0115] The reaction temperature in the step (1) is generally in therange of from 125 to 160° C., preferably from 130 to 150° C.

[0116] When the reaction temperature is lower than 125° C., the rate ofthe transesterification reaction becomes low and hence the reaction timebecomes long.

[0117] On the other hand, when the reaction temperature is higher than160° C., the diol (I) (1,3-propanediol) bonded to the terminals of thecopolycarbonate prepolymer is likely to get easily eliminated as atrimethylene carbonate, thus rendering it difficult to satisfactorilyincrease the molecular weight of the obtained copolycarbonateprepolymer.

[0118] Further, when the reaction temperature is higher than 160° C.,the following disadvantage also occurs. In the case where ethylenecarbonate is used as the carbonate compound (III), when the reactiontemperature is higher than 160° C., the ethylene carbonate undergoes adecarboxylation, thus converting the ethylene carbonate into an ethyleneoxide. The formed ethylene oxide reacts with the terminal hydroxylgroups of the diol (I) or (II), thus producing a diol containing anether linkage. The formed ether linkage-containing diol gets polymerizedin substantially the same manner as the diols (I) and (II), thusproducing a copolycarbonate prepolymer containing an ether linkage. Whenthis prepolymer is subjected to the step (2) described below, acopolycarbonate diol containing an ether linkage is obtained. Athermoplastic polyurethane obtained using such copolycarbonate diolexhibits poor resistance to heat and light.

[0119] In addition, in the case where 1,4-butanediol or 1,5-pentanediolis used as the diol (II), when the reaction temperature is higher than160° C., there is a disadvantage in that a product formed by thereaction between the diol (II) and ethylene carbonate, and/or the diol(II) bonded to the terminals of the copolycarbonate prepolymer producedin the reaction is likely to be easily eliminated as a cyclic ether(namely, a tetrahydrofuran and/or a tetrahydropyran).

[0120] With respect to the pressure for the reaction, it is generally inthe range of from atmospheric pressure to 0.5 kPa; however, due to thereason as mentioned above, it is preferred that the reaction isperformed under reduced pressure.

[0121] With respect to the timing of the termination of thepolymerization reaction, there is no particular limitation; however,when the polymerization reaction is terminated at an early stage ofreaction where the conversion of diol (as described below) is still low,there is a disadvantage in that not only does the yield of the obtainedcopolycarbonate prepolymer become low, but also the reaction time of thestep (2) as described below becomes long.

[0122] On the other hand, when the polymerization reaction is performedso as to achieve a very high conversion of diol, there is a problem inthat, as the reaction proceeds, the diols (I) and (II) and the carbonatecompound (III) contained in the reaction mixture in the reactor areconsumed and hence the concentrations of the diols (I) and (II) and thecarbonate compound (III) in the reaction mixture become low, thusdecreasing the polymerization rate. As a result, an extremely longperiod of time is required for achieving a very high conversion of diol.

[0123] Therefore, it is generally preferred that the polymerizationreaction in the step (1) is terminated when the conversion of diol hasreached 50 to 95%. The conversion of diol is represented by thefollowing formula:

Conversion of diol (%)={1−(A/B)}×100

[0124] wherein:

[0125] A is the total molar amount of diols (I) and (II) contained inthe reaction mixture; and

[0126] B is the total molar amount of diols (I) and (II) charged intothe reactor.

[0127] The value of A as mentioned above is obtained by a method inwhich the reaction mixture obtained in the step (1) is subjected to gaschromatography (GC) analysis so as to determine the amounts (in mole) of1,3-propanediol, 1,4-butanediol, 1,5-pentanediol and 1,6-hexanediol, andthe value of A is calculated from the determined amounts of these diols.If desired, before being subjected to the GC analysis, the reactionmixture may be appropriately diluted with an organic solvent, such asacetone and the like.

[0128] The conditions for the GC analysis are as follows.

[0129] Apparatus: GC-14B (manufactured and sold by Shimadzu Corporation,Japan)

[0130] Column: DB-WAX (manufactured and sold by J & W, U.S.A.)

[0131] (column length: 30 m, film thickness: 0.25 μm)

[0132] Detector: FID (flame ionization detector)

[0133] Internal standard: diethylene glycol diethyl ether

[0134] Temperature: the temperature was first maintained at 60° C. for 5minutes and then elevated to 250° C. at a rate of 10° C./min.

[0135] The copolycarbonate prepolymer obtained in the step (1) generallyexhibits a degree of polymerization in the range of from 2 to 10.Generally, the degree of polymerization of the copolycarbonateprepolymer is controlled by adjusting the amount of the hydroxylgroup-containing by-product removed from the reaction system.

[0136] Hereinbelow, an explanation is made of the step (2) of theprocess for producing the copolycarbonate diol of the present invention.

[0137] In the step (2), the copolycarbonate prepolymer obtained in thestep (1) is subjected to a self-condensation reaction, thereby producingthe copolycarbonate diol of the present invention. Since thisself-condensation reaction is a transesterification, as the reactionproceeds, the diols (I) and (II) are eliminated from the terminals ofthe copolycarbonate diol being produced. Since the transesterificationreaction is an equilibrium reaction, when the diols (I) and (II)accumulate in the reaction system, the polymerization does notsatisfactorily advance. Therefore, it is preferred that thepolymerization reaction is performed while removing the eliminated diols(I) and (II) from the reaction system.

[0138] Generally, the removal of the eliminated diols (I) and (II) fromthe reaction system is performed by evaporation and hence, in the step(2), the polymerization reaction is generally performed under reducedpressure.

[0139] Specifically, the step (2) is generally performed as follows.

[0140] The contents (reaction mixture) of the reactor are heated underreduced pressure to effect a self-condensation reaction while removingto the outside of the reaction system a vapor being generated which iscomprised mainly of the eliminated diols (I) and (II). Differing fromthe case of the step (1), in the step (2), for efficiently removing thediols (I) and (II) as they are eliminated from the copolycarbonate diolbeing produced, it is preferred that the vapor comprised mainly of theeliminated diols (I) and (II) is directly removed from the reactionsystem to the outside, without using a fractionating column or the like.In addition, it is preferred that, by using a thin film evaporator, thereaction mixture obtained in the step (1) is caused to flow down in theform of a thin film in the evaporator, thereby evaporating off theeliminated diols (I) and (II) while performing the reaction in the step(2).

[0141] In the step (2), generally, the reaction mixture obtained in thestep (1), as such, namely without being purified, is subjected to aself-condensation reaction. The reaction mixture may contain unreacteddiols (I) and (II) or unreacted carbonate compound (III); however, theseunreacted substances are removed either in the depressurizationoperation immediately upon initiation of the reaction in the step (2) orat the early stage of the reaction in the step (2).

[0142] In the step (2), the reaction temperature is generally in therange of from 125 to 170° C., preferably from 130 to 150° C.

[0143] The diols (I) and (II) and the carbonate compound (III) used asthe raw materials in the step (1), may cause a side reaction under hightemperature conditions, thus forming an ether compound whichdeteriorates the properties of the thermoplastic polyurethane producedusing the obtained copolycarbonate diol. In the step (2), however, thereaction is performed under conditions wherein the diols (I) and (II)and the carbonate compound (III) are present only in small amounts inthe reaction system; in addition, as the reaction proceeds, the amountsof the diols (I), (II) and the carbonate compound (III) becomesubstantially zero. Hence, an ether compound is formed only in a verysmall amount in the step (2). Therefore, in the step (2), the reactiontemperature can be higher than in the step (1).

[0144] However, when the reaction temperature is higher than 170° C.,the decomposition (i.e., depolymerization) of the obtainedcopolycarbonate diol is likely to occur, leading to a problem in that acopolycarbonate diol having the desired composition and molecular weightcannot be obtained.

[0145] On the other hand, when the reaction temperature is lower than125° C., the reaction rate is low and hence the reaction time becomeslong.

[0146] With respect to the pressure (namely, the degree of vacuum) forthe reaction in the step (2), it is generally in the range of from 0.10to 10 kPa. For saving the reaction time, it is preferred that thepressure is in the range of from 0.2 to 2 kPa.

[0147] The lower the pressure for the reaction (namely, the higher thedegree of vacuum), the higher the facility in removal of eliminateddiols (I) and (II) from the reaction system, and hence the higher therate of the reaction. However, for increasing the degree of vacuum, useof a higher performance vacuum pump is required. Use of such vacuum pumpposes problems in that such vacuum pump is not easily available, andthat, even when such vacuum pump is available, the equipment costbecomes high.

[0148] If desired, the polymerization reaction and the self-condensationreaction can be performed in the presence of a catalyst. The catalystcan be appropriately selected from the catalysts conventionally used fora transesterification.

[0149] Examples of such catalysts include metals, such as lithium,sodium, potassium, rubidium, cesium, magnesium, calcium, strontium,barium, zinc, aluminum, titanium, cobalt, germanium, tin, lead,antimony, arsenic and cerium, and compounds thereof. Examples of metalcompounds include salts, alkoxides and organometal compounds. Amongthese, especially preferred are titanium compounds, such as titaniumtetrabutoxide, titanium tetra-n-propoxide and titaniumtetra-isopropoxide; tin compounds, such as dibutyltin oxide, tinoxalate, dibutyltin dimaleate and dibutyltin dilaurate; and leadcompounds, such as tetraphenyllead, lead acetate and lead stearate.

[0150] The amount of catalyst is generally in the range of from 0.00001to 1% by weight, based on the total weight of the raw materials chargedinto the reactor.

[0151] In the case where the copolycarbonate diol of the presentinvention is used as a material for producing a thermoplastic elastomer,especially a polyester polycarbonate elastomer, when a residue of thecatalyst is present in the copolycarbonate diol, there is a problem inthat a transesterification occurs between the hard segment (i.e.,polyester), and the soft segment (i.e., polycarbonate diol) due to thepresence of the residual catalyst, leading to a deterioration of theproperties of the thermoplastic elastomer obtained. For preventing theoccurrence of such problem, it is preferred that the polymerization isperformed without using a catalyst. On the other hand, when thepolymerization is performed in the presence of a catalyst, it isrequired that, prior to the use of the copolycarbonate diol as amaterial for producing a thermoplastic elastomer, the copolycarbonatediol be purified so as to remove the residual catalyst and to preventthe occurrence of the deterioration of the properties of thethermoplastic elastomer derived therefrom. From the viewpoint ofreducing the work load of the purification operation, when thepolymerization reaction is performed in the presence of a catalyst, itis preferred that the catalyst is used in an amount in the range of from0.00001 to 0.0001% by weight, based on the total weight of the rawmaterials charged into the reactor.

[0152] The thus obtained copolycarbonate diol of the present inventionand a polyisocyanate are subjected to copolymerization, to therebyobtain the thermoplastic polyurethane of the present invention. Thethermoplastic polyurethane of the present invention exhibits excellentproperties with respect to flexibility, heat resistance, low temperatureproperties, weathering resistance, strength, and molding processability.Therefore, the thermoplastic polyurethane of the present invention isextremely useful as a material for producing various shaped articles.Hereinbelow, an explanation is made of the thermoplastic polyurethane ofthe present invention.

[0153] Examples of polyisocyanates used for producing the thermoplasticpolyurethane of the present invention include conventional aromaticdiisocyanates, such as 2,4-tolylene diisocyanate, 2,6-tolylenediisocyanate, a mixture of 2,4-tolylene diisocyanate and 2,6-tolylenediisocyanate (TDI), diphenylmethane-4,4′-diisocyanate (MDI),naphthalene-1,5-diisocyanate (NDI), 3,3′-dimethyl-4,4′-biphenylenediisocyanate, crude TDI, polymethylenepolyphenyl isocyanate, crude MDI,xylylene diisocyanate (XDI) and phenylene diisocyanate; conventionalaliphatic diisocyanates, such as 4,4′-methylenebiscyclohexyldiisocyanate (hydrogenated MDI), hexamethylene diisocyanate (HMDI),isophorone diisocyanate (IPDI) and cyclohexane diisocyanate(hydrogenated XDI); and modified products thereof, such as isocyanurateproducts, carbodimide products and biuret products.

[0154] In the present invention, if desired, a chain extender may beused as a copolymerizable component. As the chain extender, there may beemployed a customary chain extender used for producing a polyurethane,as described in, for example, “Saishin Poriuretan Oyo-Gijutsu (LatestApplication Techniques of Polyurethane)” edited by Keiji Iwata, pp.25-27, CMC, Japan, 1985. Examples of chain extenders include water, alow molecular weight polyol, a polyamine and the like. Depending on theuse of the thermoplastic polyurethane, if desired, a conventional highmolecular weight polyol may also be used in combination with thecopolycarbonate diol of the present invention as long as the propertiesof the produced polyurethane are not adversely affected. As theconventional high molecular weight polyol, there may be employed thosewhich are described in, for example, pp. 12-23 of “Poriuretan Foumu(Polyurethane Foam)” by Yoshio Imai, published by Kobunshi Kankokai,Japan, 1987. Examples of high molecular weight polyols include apolyester polyol and a polyether carbonate having a polyoxyalkylenechain (i.e., a polyether carbonate polyol).

[0155] Specifically, a low molecular weight polyol used as a chainextender is generally a diol monomer having a molecular weight of notmore than 300. Examples of such low molecular weight polyols includealiphatic diols, such as ethylene glycol, 1,3-propanediol,1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol and1,10-decanediol.

[0156] Further examples of low molecular weight polyols used as a chainextender include alicyclic diols, such as 1,1-cyclohexanedimethanol,1,4-cyclohexanedimethanol and tricyclodecanedimethanol; xylylene glycol,bis(p-hydroxy)diphenyl, bis(p-hydroxyphenyl)propane,2,2-bis[4-(2-hydroxyethoxy)phenyl]propane, bis[4(2-hydroxy)phenyl]sulfone and 1,1-bis[4-(2-hydroxyethoxy)phenyl] cyclohexane. As achain extender, ethylene glycol and 1,4-butanediol are preferred.

[0157] For producing the thermoplastic polyurethane of the presentinvention, a urethane-forming technique known in the art may beemployed. For example, the copolycarbonate diol of the present inventionis reacted with an organic polyisocyanate under atmospheric pressure ata temperature of from room temperature to 200° C. to form athermoplastic polyurethane. When a chain extender is optionally used, achain extender may be added to the reaction system either beforeinitiating the reaction or during the reaction. For a specific methodfor producing a thermoplastic polyurethane, reference can be made toU.S. Pat. No. 5,070,173.

[0158] In the polyurethane-forming reaction, a conventionalpolymerization catalyst, such as a tertiary amine and an organic salt ofa metal, e.g., tin or titanium, may be employed (see, for example,“Poriuretan Jushi (Polyurethane Resin)” written by Keiji Iwata, pages 23to 32, published in 1969 by The Nikkan Kogyo Shimbun, Ltd., Japan). Thepolyurethane-forming reaction may be performed in a solvent. Preferredexamples of solvents include dimethylformamide, diethylformamide,dimethylacetamide, dimethylsulfoxide, tetrahydrofuran, methyl isobutylketone, dioxane, cyclohexanone, benzene, toluene and ethyl cellosolve.

[0159] In the polyurethane-forming reaction, a compound having only oneactive hydrogen atom which is capable of reacting with an isocyanategroup, for example, a monohydric alcohol, such as ethyl alcohol orpropyl alcohol, and a secondary amine, such as diethylamine ordi-n-propylamine, may be used as a reaction terminator.

[0160] In the present invention, it is preferred that stabilizers, suchas heat stabilizers (for example, antioxidants) and light stabilizers,are added to the thermoplastic polyurethane.

[0161] Examples of antioxidants (heat stabilizers) include aliphatic,aromatic or alkyl-substituted aromatic esters of phosphoric acid orphosphorous acid; hypophosphinic acid derivatives; phosphorus-containingcompounds, such as phenylphosphonic acid, phenylphosphinic acid,diphenylphosphonic acid, polyphosphonate, dialkylpentaerythritoldiphosphite and a dialkylbisphenol A diphosphite; phenol derivatives,especially, hindered phenol compounds; sulfur-containing compounds, suchas thioether type compounds, dithioacid salt type compounds,mercaptobenzimidazole type compounds, thiocarbanilide type compounds andthiodipropionic acid esters; and tin-containing compounds, such as tinmalate and dibutyltin monooxide.

[0162] In general, antioxidants can be classified into primary,secondary and tertiary antioxidants. As hindered phenol compounds usedas a primary antioxidant, Irganox 1010 (trade name) (manufactured andsold by CIBA-GEIGY, Switzerland) and Irganox 1520 (trade name)(manufactured and sold by CIBA-GEIGY, Switzerland) are preferred. Asphosphorus-containing compounds used as a secondary antioxidant, PEP-36,PEP-24G and HP-10 (each being a trade name) (each manufactured and soldby ASAHI DENKA K.K., Japan) and Irgafos 168 (trade name) (manufacturedand sold by CIBA-GEIGY, Switzerland) are preferred. Further, assulfur-containing compounds used as a tertiary antioxidant, thioethercompounds, such as dilaurylthiopropionate (DLTP) anddistearylthiopropionate (DSTP) are preferred.

[0163] Examples of light stabilizers include UV absorber type lightstabilizers and radical scavenger type light stabilizers. Specificexamples of UV absorber type light stabilizers include benzotriazolecompounds and benzophenone compounds. Specific examples of radicalscavenger type light stabilizers include hindered amine compounds.

[0164] The above-exemplified stabilizers can be used individually or incombination. The stabilizers are added to the thermoplastic polyurethanein an amount of from 0.01 to 5 parts by weight, preferably from 0.1 to 3parts by weight, more preferably from 0.2 to 2 parts by weight, relativeto 100 parts by weight of the thermoplastic polyurethane.

[0165] If desired, a plasticizer may be added to the thermoplasticpolyurethane of the present invention. Examples of plasticizers includephthalic esters, such as dioctyl phthalate, dibutyl phthalate, diethylphthalate, butylbenzyl phthalate, di-2-ethylhexyl phthalate, diisodecylphthalate, diundecyl phthalate and diisononyl phthalate; phosphoricesters, such as tricresyl phosphate, triethyl phosphate, tributylphosphate, tri-2-ethylhexyl phosphate, trimethylhexyl phosphate,tris-chloroethyl phosphate and tris-dichloropropyl phosphate; aliphaticesters, such as octyl trimellitate, isodecyl trimellitate, trimelliticesters, dipentaerythritol esters, dioctyl adipate, dimethyl adipate,di-2-ethylhexyl azelate, dioctyl azelate, dioctyl sebacate,di-2-ethylhexyl sebacate and methylacetyl ricinoleate; pyromelliticesters, such as octyl pyromellitate; epoxy plasticizers, such asepoxidized soyabean oil, epoxidized linseed oil and epoxidized fattyacid alkyl esters; polyether plasticizers, such as adipic ether esterand polyether; liquid rubbers, such as liquid NBR, liquid acrylic rubberand liquid polybutadiene; and non-aromatic paraffin oil.

[0166] The above-exemplified plasticizers may be used individually or incombination. The amount of the plasticizer added to the thermoplasticpolyurethane is appropriately chosen in accordance with the requiredhardness and properties of the thermoplastic polyurethane; however, ingeneral, it is preferred that the plasticizer is used in an amount offrom 0.1 to 50 parts by weight, relative to 100 parts by weight of thethermoplastic polyurethane.

[0167] In addition, other additives, such as inorganic fillers,lubricants, colorants, silicon oil, foaming agents, flame retardants andthe like, may be added to the thermoplastic polyurethane of the presentinvention. Examples of inorganic fillers include calcium carbonate,talc, magnesium hydroxide, mica, barium sulfate, silicic acid (whitecarbon), titanium oxide and carbon black. These additives may be addedto the thermoplastic polyurethane of the present invention in an amountwhich is generally used for the conventional thermoplastic polyurethane.

[0168] The Shore D hardness of the thermoplastic polyurethane of thepresent invention is preferably in the range of from 20 to 70, morepreferably from 25 to 50. When the Shore D hardness is less than 20,heat stability and scratch resistance become low. On the other hand,when the Shore D hardness is more than 70, low temperature propertiesand softness become unsatisfactory.

[0169] Further, the melt flow rate (as measured at 230° C. under a loadof 2.16 kg; hereinafter, abbreviated to “MFR”) of the thermoplasticpolyurethane of the present invention is preferably from 0.5 to 100 g/10minutes, more preferably from 5 to 50 g/10 minutes, still morepreferably from 10 to 30 g/10 minutes. When MFR is less than 0.5 g/10minutes, the injection moldability of the thermoplastic polyurethanebecomes poor and the injection molding is likely to result in“incomplete filling” (that is, the filling of the mold cavity becomesincomplete). On the other hand, when MFR is more than 100 g/10 minutes,not only the mechanical properties (such as tensile strength andelongation at break) and abrasion resistance, but also low temperatureproperties are lowered.

[0170] With respect to the molecular weight of the thermoplasticpolyurethane of the present invention, it is preferred that each of thenumber average molecular weight (Mn) and weight average molecular weight(Mw) of the thermoplastic polyurethane is in the range of from 10,000 to200,000. Each of Mn and Mw is measured by GPC analysis, using acalibration curve obtained with respect to standard polystyrene samples.

[0171] The thus obtained thermoplastic polyurethane of the presentinvention exhibits excellent properties with respect to flexibility,heat resistance, low temperature properties, weathering resistance,strength, and molding processability. Therefore, the thermoplasticpolyurethane of the present invention is extremely useful as a materialfor producing various shaped articles, such as automobile parts, partsfor household electric appliances, toys and sundry goods. Especially,the thermoplastic polyurethane of the present invention is useful forproducing shaped articles which are required to have high strength, suchas hoses, sheets and industrial belts; and shaped articles which arerequired to have high flexibility, such as interior and exterior partsfor automobiles (for example, window moles, bumpers, skin parts for aninstrument panel, and grips), spandexes, bands for wristwatches, andshoe soles.

BEST MODE FOR CARRYING OUT THE INVENTION

[0172] Hereinbelow, the present invention will be described in moredetail with reference to the following Examples and ComparativeExamples; however, they should not be construed as limiting the scope ofthe present invention.

[0173] In the following Examples and Comparative Examples, variousmeasurements and analyses were performed by the following methods.

[0174] (1) Number Average Molecular Weight (Mn) of Polycarbonate Diol

[0175] The acid values of the polycarbonate diols obtained in Examplesand Comparative Examples were measured (wherein the acid value isdefined as the amount (mg) of potassium hydroxide (KOH) required forneutralizing the acidic groups in 1 g of a polycarbonate diol). As aresult, it was found that none of the polycarbonate diols had an acidvalue exceeding 0.01.

[0176] The polycarbonate diols were examined by ¹³C-NMR spectroscopy(nuclear magnetic resonance measurement apparatus: α-400; manufacturedand sold by JEOL LTD., Japan) (observation frequency: 100 MHz,accumulation number: 10,000, and measuring temperature: 20° C.). In the¹³C-NMR spectra of the polycarbonate diols, no signal ascribed to anacid group, such as a carboxyl group, was observed.

[0177] From the results of the measurements, it was found that thepolycarbonate diols contained substantially no acid groups, that is,substantially all terminal groups of the polycarbonate diols werehydroxyl groups.

[0178] Thus, it was found that the number average molecular weights (Mn)of the polycarbonate diols were able to be calculated from the hydroxylvalues of the polycarbonate diols (wherein the hydroxyl value can bemeasured by the method as shown in item (2) below). Therefore, thenumber average molecular weight (Mn) of each polycarbonate diol wascalculated from the hydroxyl value (mg−KOH/g) thereof in accordance withthe following formula:

Mn=(2×56.11×1,000)÷hydroxyl value.

[0179] (2) Hydroxyl Value of Polycarbonate Diol

[0180] An acetylation reagent was prepared by adding pyridine to 12.5 gof acetic anhydride so that the total volume became 50 ml.

[0181] 2.5 to 5.0 g of a polycarbonate diol obtained was preciselyweighed out and placed in a 100 ml eggplant-shaped flask. 5 ml of theacetylation reagent prepared above and 10 ml of toluene were put intothe eggplant-shaped flask by means of a transfer pipette, and theresultant mixture in the eggplant-shaped flask was then heated at 100°C. for 1 hour while stirring to thereby obtain a reaction mixture.

[0182] 2.5 ml of distilled water was put into the eggplant-shaped flaskcontaining the obtained reaction mixture by means of a transfer pipette,and the resultant mixture in the eggplant-shaped flask was furtherstirred for 10 minutes, followed by cooling for a few minutes. 12.5 mlof ethanol and a few drops of a phenolphthalein solution as an indicatorwere added to the mixture in the eggplant-shaped flask to obtain asolution. The obtained solution was titrated with a 0.5 mol/l potassiumhydroxide solution in ethanol.

[0183] On the other hand, a blank test was performed by repeatingsubstantially the same procedure as mentioned above, except that apolycarbonate diol was not used.

[0184] Then, based on the results of these operations, the hydroxylvalue of the polycarbonate diol was calculated in accordance with thefollowing formula:

Hydroxyl value (mg−KOH/g)=((B−A)×28.5×f)/C

[0185] wherein:

[0186] A represents the amount (ml) of the ethanol solution of potassiumhydroxide used for the titration;

[0187] B represents the amount (ml) of the ethanol solution of potassiumhydroxide used for the titration performed in the blank test;

[0188] C represents the weight (g) of the polycarbonate diol; and

[0189] f represents the factor of the ethanol solution of potassiumhydroxide.

[0190] Hereinafter, the hydroxyl value is referred to as the “OH value”.

[0191] (3) Composition of the Recurring Units of Polycarbonate Diol

[0192] 1 g of a copolycarbonate diol was weighed out and placed in a 100ml eggplant-shaped flask. 30 g of ethanol and 4 g of potassium hydroxidewere added to the copolycarbonate diol in the eggplant-shaped flask, anda reaction was performed at 100° C. for 1 hour, thereby obtaining areaction mixture.

[0193] The obtained reaction mixture was cooled to room temperature, anda few drops of a phenolphthalein solution as an indicator were added tothe reaction mixture, followed by neutralization using hydrochloricacid, to obtain a mixture. The obtained mixture was cooled in arefrigerator for 1 hour to thereby precipitate a salt (potassiumchloride) formed by neutralization. The precipitated potassium chloridewas removed by filtration and the resultant filtrate was analyzed by gaschromatography to thereby determine the amounts (mol) of1,3-propanediol, 1,4-butanediol, 1,5-pentanediol and 1,6-hexanediolwhich were contained in the filtrate.

[0194] The composition of recurring units was evaluated as the ratio(mol %) of recurring units derived from 1,3-propanediol, based on thetotal molar amount of recurring units derived from the above-mentioneddiols. The composition of recurring units of the polycarbonate diol wascalculated in accordance with the following formula:

Composition of recurring units (mol %)=(D/E)×100

[0195] wherein:

[0196] D represents the molar amount of 1,3-propanediol; and

[0197] E represents the total molar amount of the above-mentioned diols.

[0198] With respect to the copolycarbonate diol obtained in ComparativeExample 3 (wherein the copolycarbonate diol contained no recurring unitsderived from 1,3-propanediol), the composition of recurring units wasevaluated as the ratio (mol %) of recurring units derived from1,5-pentanediol, based on the total molar amount of recurring unitsderived from 1,5-pentanediol and 1,6-hexanediol. That is, thecomposition of recurring units of the copolycarbonate diol obtained inComparative Example 3 was determined in substantially the same manner asmentioned above, except that, in the above-mentioned formula, Drepresents the molar amount of 1,5-pentanediol and E represents thetotal molar amount of 1,5-pentanediol and 1,6-hexanediol.

[0199] Conditions for gas chromatography were as follows. Apparatus:GC-14B (manufactured and sold by Shimadzu Corporation, Japan) Column:DB-WAX (manufactured and sold by J & W, U.S.A.) (column length: 30 m;film thickness: 0.25 μm) Detector: FID (flame ionization detector)Internal standard: diethylene glycol diethyl ether Temperature: thetemperature was first maintained at 60° C. for 5 minutes and thenelevated to 250° C. at a rate of 10° C./min.

[0200] (4) Viscosity of Polycarbonate Diol

[0201] The viscosity was measured at 50° C. in accordance with ASTM,D1986, p.193 to 194, using the digital Brookfield viscometer LVTDV-1(manufactured and sold by BROOKFIELD ENGINEERING LABORATORIES INC.,U.S.A.) (wherein the spindle (rotor) No. 34 was used).

[0202] (5) Melting Temperature (Tm) and Glass Transition Temperature(Tg) of Polycarbonate Diol

[0203] About 10 mg of a polycarbonate diol was precisely weighed out andplaced in an aluminum pan and subjected to measurement using adifferential scanning calorimeter, in order to determine the meltingtemperature and glass transition temperature of the polycarbonate diolunder the following analysis conditions: Apparatus: DSC220C(manufactured and sold by Seiko Instruments Inc, Japan) Temperaturerange of measurement: −120 to 70° C. Temperature elevation rate: 10°C./min.

[0204] (6) Number Average Molecular Weight and Weight Average MolecularWeight of Thermoplastic Polyurethane

[0205] The number average molecular weight and weight average molecularweight of a thermoplastic polyurethane were measured by gel permeationchromatography (GPC) using a calibration curve obtained with respect tostandard monodisperse polystyrene samples.

[0206] (7) Various Mechanical Properties of Thermoplastic Polyurethane

[0207] Measurements were performed as follows.

[0208] (i) Shore ‘D’ Hardness [−]:

[0209] Shore ‘D’ hardness was measured in accordance with ASTM D2240, Dtype, at 23° C.

[0210] (ii) Tensile Stress [kgf/cm²]:

[0211] Tensile stress was measured in accordance with JIS K6251 (using adumbbell No. 3 prescribed therein). A pressed sheet having a thicknessof 2 mm was used as a test sample.

[0212] (iii) Tensile Strength at 100% Elongation [kgf/cm²]:

[0213] Tensile strength was measured in accordance with JIS K6251 (usinga dumbbell No. 3 prescribed therein). A pressed sheet having a thicknessof 2 mm was used as a test sample.

[0214] (iv) Elongation [%]:

[0215] Elongation was measured in accordance with JIS K6251 (using adumbbell No. 3 prescribed therein). A pressed sheet having a thicknessof 2 mm was used as a test sample.

[0216] (v) Impact Resilience [%]:

[0217] Impact resilience was measured in accordance with JIS K6255(using a Lübke pendulum, 23° C.).

EXAMPLE 1

[0218] 305 g of 1,3-propanediol, 355 g of 1,6-hexanediol and 760 g ofethylene carbonate were charged into a 2-liter separable flask equippedwith a stirrer, a thermometer and an Oldershaw distillation columnhaving a vacuum jacket and having a reflux head at the top thereof. Theresultant mixture in the separable flask was stirred at 70° C. to obtaina solution. To the obtained solution was added 0.015 g of lead acetatetrihydrate as a catalyst, to obtain a mixture.

[0219] The flask was connected to a vacuum pump, and the mixture in theflask was subjected to a polymerization reaction for 12 hours whilestirring under conditions wherein the degree of vacuum was from 1.0 to1.5 kPa and the internal temperature of the flask was 140° C. (whereinthe flask was heated in an oil bath having a temperature of 175° C.), toobtain a reaction mixture. During the reaction, a portion of thedistillate was withdrawn through the reflux head so that the refluxratio became 4.

[0220] Then, the Oldershaw distillation column was removed from theseparable flask, and a condenser and a receiver were attached to theseparable flask to thereby form a vacuum distillation apparatus. Under avacuum of 0.5 kPa, the separable flask was heated in an oil bath (thebath temperature: 180° C.) so that the internal temperature of theseparable flask was elevated to a temperature in the range of from 140to 150° C., to thereby distill off 1,3-propanediol, 1,6-hexanediol,ethylene glycol (which was derived from ethylene carbonate) and ethylenecarbonate which were contained in the reaction mixture in the flask.

[0221] Thereafter, the temperature of the oil bath was elevated to 185°C. while maintaining the degree of vacuum in the flask at 0.5 kPa,thereby elevating the internal temperature of the separable flask to atemperature in the range of from 160 to 165° C., and the heating wascontinued for 4 hours to effect a reaction while distilling off1,3-propanediol and 1,6-hexanediol which were by-produced during thereaction.

[0222] As a result, 721 g of a copolycarbonate diol was obtained. Theobtained copolycarbonate diol is hereinafter referred to as “pc-a”. Thecopolycarbonate diol pc-a was a viscous liquid at room temperature.

[0223] The properties of pc-a, i.e., OH value, number average molecularweight, recurring unit composition (composition, mol %), meltingtemperature, glass transition temperature and viscosity, are shown inTable 1.

EXAMPLE 2

[0224] 228 g of 1,3-propanediol, 270 g of 1,4-butanediol and 530 g ofethylene carbonate were charged into a 2-liter separable flask equippedwith a stirrer, a thermometer and an Oldershaw distillation columnhaving a vacuum jacket and having a reflux head at the top thereof. Theresultant mixture in the separable flask was stirred at 70° C. to obtaina solution. To the obtained solution was added 0.014 g of lead acetatetrihydrate as a catalyst, to obtain a mixture.

[0225] The flask was connected to a vacuum pump, and the mixture in theflask was subjected to a polymerization reaction for 20 hours whilestirring under conditions wherein the degree of vacuum was from 1.0 to1.5 kPa and the internal temperature of the flask was 130° C. (whereinthe flask was heated in an oil bath having a temperature of 170° C.), toobtain a reaction mixture. During the reaction, a portion of thedistillate was withdrawn through the reflux head so that the refluxratio became 4.

[0226] Then, the Oldershaw distillation column was removed from theseparable flask, and a condenser and a receiver were attached to theseparable flask to thereby form a vacuum distillation apparatus. Under avacuum of 0.5 kPa, the separable flask was heated for 4 hours in an oilbath (the bath temperature: 170° C.) so that the internal temperature ofthe separable flask was maintained at a temperature in the range of from130 to 140° C., to thereby effect a reaction. During the reaction,1,3-propanediol, 1,4-butanediol, ethylene glycol (which was derived fromethylene carbonate) and ethylene carbonate which were contained in thereaction mixture in the flask, were distilled off.

[0227] As a result, 514 g of a copolycarbonate diol was obtained. Theobtained copolycarbonate diol is hereinafter referred to as “pc-b”. Thecopolycarbonate diol pc-b was a viscous liquid at room temperature.

[0228] The properties of pc-b, i.e., OH value, number average molecularweight, recurring unit composition (composition, mol %), meltingtemperature, glass transition temperature and viscosity, are shown inTable 1.

COMPARATIVE EXAMPLE 1

[0229] Substantially the same procedure as in Example 1 was repeatedexcept that the amounts of 1,3-propanediol, ethylene carbonate and leadacetate trihydrate were changed to 420 g, 440 g and 0.010 g,respectively, and that 1,6-hexanediol was not used, to thereby obtain364 g of a polycarbonate diol. Hereinafter, the thus producedpolycarbonate diol is referred to as “pc-c”. The polycarbonate diol pc-cwas a viscous liquid at room temperature.

[0230] The properties of pc-c, i.e., OH value, number average molecularweight, recurring unit composition (composition, mol %), meltingtemperature, glass transition temperature and viscosity, are shown inTable 1.

COMPARATIVE EXAMPLE 2

[0231] 472 g of 1,6-hexanediol and 344 g of ethylene carbonate werecharged into a 2-liter separable flask equipped with a stirrer, athermometer and an Oldershaw distillation column having a vacuum jacketand having a reflux head at the top thereof. The resultant mixture inthe separable flask was stirred at 70° C. to obtain a solution. To theobtained solution was added 0.010 g of lead acetate trihydrate as acatalyst, to obtain a mixture.

[0232] The flask was connected to a vacuum pump, and the mixture in theflask was subjected to a polymerization reaction for 8 hours whilestirring under conditions wherein the degree of vacuum was from 3.0 to4.2 kPa and the internal temperature of the flask was 160° C. (whereinthe flask was heated in an oil bath having a temperature of 190° C.), toobtain a reaction mixture. During the reaction, a portion of thedistillate was withdrawn through the reflux head so that the refluxratio became 4.

[0233] Then, the Oldershaw distillation column was removed from theseparable flask, and a condenser and a receiver were attached to theseparable flask to thereby form a vacuum distillation apparatus. Under avacuum of 0.5 kPa, the separable flask was heated in an oil bath (thebath temperature: 190° C.) so that the internal temperature of theseparable flask was elevated to a temperature in the range of from 160to 170° C., to thereby distill off unreacted diols and ethylenecarbonate which were contained in the reaction mixture in the flask.

[0234] Thereafter, the temperature of the oil bath was elevated to 200°C. while maintaining the degree of vacuum in the flask at 0.5 kPa,thereby elevating the internal temperature of the separable flask to atemperature in the range of from 170 to 190° C., and the heating wascontinued for 3 hours to effect a reaction while distilling off a diolwhich was formed during the reaction.

[0235] As a result, 457 g of a polycarbonate diol was obtained. Theobtained polycarbonate diol is hereinafter referred to as “pc-d”. Thepolycarbonate diol pc-d was a white solid at room temperature.

[0236] The properties of pc-d, i.e., OH value, number average molecularweight, recurring unit composition (composition, mol %), meltingtemperature, glass transition temperature and viscosity, are shown inTable 1.

COMPARATIVE EXAMPLE 3

[0237] Substantially the same procedure as in Comparative Example 2 wasrepeated except that the amounts of 1,6-hexanediol, ethylene carbonateand lead acetate trihydrate were changed to 325 g, 485 g and 0.015 g,respectively, and that 285 g of 1,5-pentanediol was used, to therebyobtain 385 g of a copolycarbonate diol. Hereinafter, the thus producedcopolycarbonate diol is referred to as “pc-e”. The copolycarbonate diolpc-e was a viscous liquid at room temperature.

[0238] The properties of pc-e, i.e., OH value, number average molecularweight, recurring unit composition (composition, mol %), meltingtemperature, glass transition temperature and viscosity, are shown inTable 1. TABLE 1 Melting Glass tran- Compo- temper- sition tem- Vis-Abbre OH sition ature- perature cosity via- value Mn (mol %) (° C.) (°C.) (cp) tion Ex. 1 61 1840 36 — −53 5340 pc-a Ex. 2 69 1630 34 — −544890 pc-b Comp. 186 600 100  — −54 887 pc-c Ex. 1 Comp. 52 2160 — 41 −5115200 pc-d Ex. 2 Comp. 56 2000  49¹⁾ — −54 7400 pc-e Ex. 3

EXAMPLE 3

[0239] 200 g of pc-a obtained in Example 1 and 80.3 g ofdiphenylmethane-4,4′-diisocyanate (MDI) were charged into a reactionvessel equipped with a stirrer, a thermometer and a condenser. Areaction of the resultant mixture was performed at 100° C. for 4 hours,thereby obtaining a prepolymer having terminal NCO groups. To theobtained prepolymer were added 30 g of 1,4-butanediol as a chainextender and 0.006 g of dibutyltin dilaurylate as a catalyst. Theresultant mixture was reacted at 140° C. for 60 minutes in a universallaboratory scale extruder (Universal Laboratory Scale Extruder KR-35type; manufactured and sold by Kasamatsu Plastic Engineering andResearch Co., Ltd., Japan) equipped with a kneader, thereby obtaining athermoplastic polyurethane. The obtained thermoplastic polyurethane wasthen pelletized using the extruder.

[0240] The number average molecular weight (Mn) and weight averagemolecular weight (Mw) of the thermoplastic polyurethane were 73,000 and126,000, respectively, as measured by GPC analysis, using a calibrationcurve obtained with respect to standard polystyrene samples. Theproperties of the thermoplastic polyurethane are shown in Table 2.

EXAMPLE 4

[0241] A thermoplastic polyurethane was produced in substantially thesame manner as in Example 3 except that pc-b obtained in Example 2 wasused as a copolycarbonate diol, instead of pc-a. The molecular weightand properties of the thermoplastic polyurethane are shown in Table 2.

EXAMPLE 5

[0242] A thermoplastic polyurethane was produced in substantially thesame manner as in Example 3 except that the amounts of MDI and1,4-butanediol were changed to 24.5 g and 4.16 g, respectively. Themolecular weight and properties of the thermoplastic polyurethane areshown in Table 2. TABLE 2 Properties of polyurethane Ex. 3 Ex. 4 Ex. 5Polycarbonate diol pc-a pc-b pc-a Number average molecular 7.3 6.9 6.6weight (x10⁴ Mn) Weight average molecular 12.6 12.8 14.2 weight (x10⁴Mw) Properties Hardness (shore D) 43 44 26 100% tensile stress 36 38 26(kgf/cm²) Tensile strength 180 200 130 (kgf/cm²) Elongation (%) 500 480660 Impact resilience (%) 58 53 62

COMPARATIVE EXAMPLES 4, 5 and 6

[0243] Thermoplastic polyurethanes were individually produced insubstantially the same manner as in Example 3 except that pc-c, pc-d andpc-e were used in Comparative Examples 4, 5, and 6, respectively,instead of pc-a. The molecular weight and properties of each of thethermoplastic polyurethanes are shown in Table 3. TABLE 3 Comp. Comp.Comp. Ex. 4 Ex. 5 Ex. 6 Polycarbonate diol pc-c pc-d pc-e Number averagemolecular 7.1 7.5 6.9 weight (x10⁴ Mn) Weight average molecular 13.213.8 12.3 weight (x10⁴ Mw) Properties Hardness (shore D) 60 53 46 100%tensile stress 63 58 46 (kgf/cm²) Tensile strength 220 210 200 (kgf/cm²)Elongation (%) 400 440 450 Impact resilience (%) 42 46 49

INDUSTRIAL APPLICABILITY

[0244] The copolycarbonate diol of the present invention is a liquidhaving low viscosity. Therefore, the copolycarbonate diol of the presentinvention is easy to handle, as compared to the conventionalpolycarbonate diols which are solids or highly viscous liquids. Hence,the copolycarbonate diol of the present invention is advantageous forvarious uses, such as a raw material for producing a thermoplasticelastomer (such as a thermoplastic polyurethane) used for producingvarious shaped articles (for example, a spandex, which is a polyurethaneelastomeric fiber); a component for a coating material or an adhesive;and a polymeric plasticizer.

[0245] The thermoplastic polyurethane of the present invention exhibitsexcellent properties with respect to flexibility, heat resistance, lowtemperature properties, weathering resistance, strength, and moldingprocessability. Therefore, the thermoplastic polyurethane of the presentinvention is extremely useful as a material for producing various shapedarticles, such as automobile parts, parts for household electricappliances, toys and sundry goods. Especially, the thermoplasticpolyurethane of the present invention is useful for producing shapedarticles which are required to have high strength, such as hoses, sheetsand industrial belts; and shaped articles which are required to havehigh flexibility, such as interior and exterior parts for automobiles(for example, window moles, bumpers, skin parts for an instrument panel,and grips), spandexes, bands for wristwatches, and shoe soles.

1. A copolycarbonate diol comprising: (a) recurring units eachrepresented by the following formula (1):

(b) recurring units each independently represented by the followingformula (2):

wherein n is 4, 5 or 6; and (c) terminal hydroxyl groups, wherein saidcopolycarbonate diol has a number average molecular weight of from 300to 20,000, and wherein the amount of said recurring units (a) is from 10to 90% by mole, based on the total molar amount of said recurring units(a) and (b).
 2. The copolycarbonate diol according to claim 1, which hasa number average molecular weight of from 500 to 10,000.
 3. Thecopolycarbonate diol according to claim 1 or 2, wherein the amount ofsaid recurring units (a) is from 20 to 80% by mole, based on the totalmolar amount of said recurring units (a) and (b).
 4. A thermoplasticpolyurethane obtained by copolymerizing the copolycarbonate diol of anyone of claims 1 to 3 with a polyisocyanate.